<template>
  <div id="app">
    <el-form :inline="true" class="demo-form-inline">

      <!-- 所属分类：级联下拉列表 -->
      <!-- 一级分类 -->
      <el-form-item label="课程类别">
        <el-select
          v-model="searchObj.subjectParentId"
          placeholder="请选择"
          @change="subjectLevelOneChanged">
          <el-option
            v-for="subject in subjectList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>

        <!-- 二级分类 -->
        <el-select v-model="searchObj.subjectId" placeholder="请选择">
          <el-option
            v-for="subject in subjectLevelTwoList"
            :key="subject.id"
            :label="subject.title"
            :value="subject.id"/>
        </el-select>
      </el-form-item>

      <!-- 标题 -->
      <el-form-item>
        <el-input v-model="searchObj.title" placeholder="课程标题"/>
      </el-form-item>
      <!-- 讲师 -->
      <el-form-item>
        <el-select
          v-model="searchObj.teacherId"
          placeholder="请选择讲师">
          <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"/>
        </el-select>
      </el-form-item>

      <el-button type="primary" icon="el-icon-search" @click="fetchData()">查询</el-button>
      <el-button type="default" @click="resetData()">清空</el-button>
    </el-form>
    <!-- 表格 -->
    <el-table :data="courses" border stripe>

      <el-table-column label="#" width="50">
        <template slot-scope="scope">
          {{ (pageNum - 1) * pageSize + scope.$index + 1 }}
        </template>
      </el-table-column>

      <el-table-column label="封面" width="200" align="center">
        <template slot-scope="scope">
          <img :src="scope.row.cover" alt="scope.row.title" width="100%">
        </template>
      </el-table-column>
      <el-table-column label="课程信息">
        <template slot-scope="scope">
          <a href="">{{ scope.row.title }}</a>
          <p>
            分类：{{ scope.row.subjectParentTitle }} > {{ scope.row.subjectTitle }}
          </p>
          <p>
            课时：{{ scope.row.lessonNum }} /
            浏览：{{ scope.row.viewCount }} /
            付费学员：{{ scope.row.buyCount }}
          </p>
        </template>
      </el-table-column>
      <el-table-column label="讲师" width="100" align="center">
        <template slot-scope="scope">
          {{ scope.row.teacherName }}
        </template>
      </el-table-column>
      <el-table-column label="价格(元)" width="100" align="center" >
        <template slot-scope="scope">
          <!-- {{ typeof '0' }}  {{ typeof 0 }} {{ '0' == 0 }} -->
          <!-- {{ typeof scope.row.price }}
          {{ typeof Number(scope.row.price) }}
          {{ typeof Number(scope.row.price).toFixed(2) }} -->

          <el-tag v-if="Number(scope.row.price) === 0" type="success">免费</el-tag>

          <!-- 前端解决保留两位小数的问题 -->
          <!-- <el-tag v-else>{{ Number(scope.row.price).toFixed(2) }}</el-tag> -->

          <!-- 后端解决保留两位小数的问题，前端不用处理 -->
          <el-tag v-else>{{ scope.row.price }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column prop="status" label="课程状态" width="100" align="center" >
        <template slot-scope="scope">
          <el-tag :type="scope.row.status === 'Draft' ? 'warning' : 'success'">{{ scope.row.status === 'Draft' ? '未发布' : '已发布' }}</el-tag>
        </template>
      </el-table-column>
      <el-table-column label="创建时间" width="140" align="center">
        <template slot-scope="scope">
          {{ scope.row.gmtCreate ? scope.row.gmtCreate.substr(0, 16) : '' }}
        </template>
      </el-table-column>

      <el-table-column label="操作" width="210" align="center">
        <template slot-scope="scope">
          <router-link :to="'/course/edit/'+scope.row.id">
            <el-button type="text" icon="el-icon-edit">修改</el-button>
          </router-link>
          <el-button type="text" icon="el-icon-delete" @click="removeById(scope.row.id)">删除</el-button>
        </template>
      </el-table-column>
    </el-table>
    <div class="block" style="text-align:center">
      <el-pagination
        :current-page="pageSize"
        :page-sizes="[3, 5, 10, 20]"
        :page-size="pageSize"
        :total="total"
        layout="total, sizes, prev, pager, next, jumper"
        @size-change="handleSizeChange"
        @current-change="handleCurrentChange"/>
    </div>
  </div>
</template>
<script>
import courseApi from '@/api/course'
import teacherApi from '@/api/teacherApi'
import subjectApi from '@/api/subject'
export default {
  data() {
    return {
      courses: [],
      pageNum: 1,
      pageSize: 3,
      total: 3,
      subjectList: [],
      searchObj: {
        subjectId: ''
      },
      teacherList: [],
      subjectLevelTwoList: []

    }
  },
  created() {
    this.getPage()
    this.getTeacherList()
    this.initCourseList()
  },
  methods: {
    getPage() {
      courseApi.getList(this.pageNum, this.pageSize).then(r => {
        this.courses = r.data.page.records
        this.total = r.data.page.total
      })
    },
    handleSizeChange(val) {
      this.pageSize = val
      this.getPage()
    },
    handleCurrentChange(val) {
      this.pageNum = val
      this.getPage()
    },
    // 初始化教师选择列表
    getTeacherList() {
      teacherApi.list().then(r => {
        this.teacherList = r.data.items
      })
    },
    // 初始化课程类别列表
    initCourseList() {
      subjectApi.getParents().then(r => {
        this.subjectList = r.data.parent
      })
    },
    // 当一级标题改变时，二级标题随之改变，并且每次改变的一级标题，二级标题都会重置
    subjectLevelOneChanged(val) {
      this.searchObj.subjectId = ''
      this.subjectList.forEach(subject => {
        if (subject.id === val) {
          this.subjectLevelTwoList = subject.children
          return
        }
      })
    },
    // 当点击查询按钮时执行查询
    fetchData() {
      courseApi.getList(this.pageNum, this.pageSize, this.searchObj).then(r => {
        this.courses = r.data.page.records
        this.total = r.data.page.total
      })
    },
    // 清空所有查询条件，并将页面刷新
    resetData() {
      this.searchObj = {}
      this.getPage()
    }

  }
}
</script>
